Fungal and Parasitic Infections of the CNS - Inova Health System

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Blastomyces dermatiditis CNS involvement uncommon: Usually is a localized granuloma with histiocytes and giant cells Even in disseminated disease, brain is involved in less than 1/3 of patients Blastomyces dermatidis •Morphology of fungus –8-15 microns –Yeast with broad-based bud on GMS, PAS –In well-fixed tissues, blastomyces has multiple nuclei –Mucicarmine stain yields very thin outline to yeast, unlike broad, thick, mucicarmine +, mucoid capsule of Cryptococcus. Fontana-Masson also is positive on Cryptococcus capsule, but not in blastomyces From JB Taxy Histoplasma capsulatum • Usually a PATHOGENIC INFECTION, also with lungonly involvement – Benign illness confined and localized in lungs and mediastinal lymph notes; at autopsy small calcified nodules may be demonstrated in spleen, liver, and occasionally kidney but NOT CNS – Active cavitating ti pulmonary lesion without t CNS involvement • Epidemiology: US midwest river valleys • Estimated that 25% of US population has contracted infection, but CNS involvement is uncommon. • Most common endemic mycosis in North America (followed by coccidiodomycosis and blastomycosis) 6
Uncommon, localized granuloma in CNS histoplasmosis, as a surgical specimen, mimicking brain tumor in an immunocompetent host (from JJ Kepes) Histoplasma capsulatum • Occasionally an OPPORTUNISTIC INFECTION, with disseminated disease in immunocompromised patients – In infancy and childhood with lymphoreticular involvement and occasional basilar meningitis – In adults with caseous nodules in systemic organs and uncommon CNS infection (7%), which, when it does occur, is basilar meningitis – Disseminated disease may be AIDS defining illness Histoplasma capsulatum •Morphology of fungus –2-4 microns –Yeast usually intracellular within macrophages; PAS+ with slight halo around yeast BUT yeast does not have a real capsule –On H&E appear MUCH SMALLER THAN ON PAS or GMS because only their central portion is visible from JJ Kepes 7
Page 1 and 2: Fungal and Parasitic Infections of
Page 3 and 4: Taxonomy simplified for the rest of
Page 5: Am J Surg Path 2007; 31:615-623 Bla
Page 9 and 10: Coccidioides immitis can be vasoinv
Page 11 and 12: Spectrum exists from bland infarcti
Page 13 and 14: Aspergillus look-alikes • Cannot
Page 15 and 16: • Morphology: - Broad hyphae 10-1
Page 17 and 18: Candida look-alikes • Torulopsis
Page 19 and 20: Nocardia and Actinomyces • Morpho
Page 21 and 22: CNS Metazoal infections: trematodes
Page 23 and 24: Lifecycle Adult tapeworm Cysticercu
Page 25 and 26: T1 Diagnosis Radiology • Scolex i
Page 27 and 28: Ameba • Entamoeba histolytica - S
Page 29 and 30: Balamuthia mandrillaris • Childre
Page 31: cysticercosis, toxoplasmosis, and t

Fungal and Parasitic Infections of the CNS - Inova Health System

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